import java.util.Scanner;

public class J1508 {
    public static int fib(int n){
        if(n <= 2){
            return 1;
        }else{
            return fib(n - 1) + fib(n - 2);
        }
    }

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        while(in.hasNextInt()) {
            int n = in.nextInt();
            System.out.println(fib(n));
        }
    }
}
